21506506043 has 8 divisors (see below), whose sum is σ = 23544549696. Its totient is φ = 19482280200.

The previous prime is 21506506037. The next prime is 21506506061. The reversal of 21506506043 is 34060560512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21506506043 - 2¹⁶ = 21506440507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21506506843) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3451193 + ... + 3457418.

It is an arithmetic number, because the mean of its divisors is an integer number (2943068712).

Almost surely, 2^21506506043 is an apocalyptic number.

21506506043 is a deficient number, since it is larger than the sum of its proper divisors (2038043653).

21506506043 is a wasteful number, since it uses less digits than its factorization.

21506506043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6908905.

The product of its (nonzero) digits is 21600, while the sum is 32.

The spelling of 21506506043 in words is "twenty-one billion, five hundred six million, five hundred six thousand, forty-three".